(a) Technical Field
The present disclosure relates to a manufacturing method for a polarization layer applied to a liquid crystal display, and particularly relates to a manufacturing method of a polarization layer for a liquid crystal display (LCD) with significantly improved light transmittance and polarization performance by lowering a pre-tilt angle.
(b) Description of the Related Art
A polarization layer for an LCD that is commercially available may be manufactured by absorbing an iodine or dichroic dye to a polyvinyl alcohol (PVA) film and stretching the PVA film in a predetermined direction, and the polarization layer may absorb a light oscillating in one direction and transmit a light oscillating in a different directions, thereby forming linear polarization. However, it may be difficult to obtain efficiency of the polarization layer of more than 50%. Also, the PVA is a water-soluble polymer such that water resistance and thermal resistance thereof may be decreased, and as a result the durability of the polarization layer may be poor, the mechanical strength for a transmissive axis direction may be weak, and the polarization layer may be contracted by heat or moisture such that the drawback of the polarization function being significantly decreased may occur.
Accordingly, an improved method for manufacturing a polarization layer with a simpler manufacturing process and an improved polarization efficiency, and a new polarization layer material is required. Accordingly, an incell-POL technique has recently been proposed for answering this requirement. There is a guest-host type in the incell-POL (ICP) technique. It is disclosed that the characteristics of this case are similar to the average value of the PVA polarizer in Advanced Material 2006 2412. In the guest-host type, a horizontal alignment layer is formed on and under an insulation substrate for the ICP, the horizontal alignment layer is subjected to a rubbing surface treatment, a spacer is formed between the upper and lower substrates, and two substrates are combined, and then a guest-host liquid crystal is filled between the two substrates. Liquid crystal molecules as the host that are filled in the substrates are uniformly arranged according to the alignment angle of the surface by the rubbing, and then ultraviolet rays (365 nm, 30 m) are irradiated to the surface of one side such that the dye as the guest is fixed.
Here, the polarization of the polarization layer is obtained through the effect of the dye absorbing light.
However, the rubbing treatment for the alignment layer of the ICP may generate a pre-tilt angle of more than two degrees on the surface of the alignment layer such that the polarization layer that is manufactured through this process may have low light transmittance, thereby decreasing the polarization efficiency.
Thus, there is a need in the art for a polarization layer with improved light transmittance and polarization performance.